This proposal examines the quarter of all ambulatory care visits which are not to physicians in private practice and are, therefore, not covered by the National Ambulatory Medical Care Survey (NAMCS). The research will provide basic information about the distribution of visits to outpatient departments and emergency rooms in New York City using the Patient Origin Information System (POIS) which has been developed by the United Hospital Fund. This data base is complete for visits to all OPDS and emergency rooms in the city for a three-month period in 1984. It contains information on diagnosis, specialty of the clinic where the patient was seen, and third party payer. Using a sample from this universe as a benchmark, physicians and facilities in New York City will be sampled from two nationwide periodic surveys conducted by the American Hospital Association and the American Medical Association. The results of the sampling, which will describe the distribution of visits to OPDs, emergency rooms, and other free-standing clinics in the city, will then be compared with the actual New York data. Supplementary data bases will be used as needed to compensate for the somewhat different drawbacks of the AHA and AMA data. No actual patient-specific data will be collected from the AHA or AMA samples. An attempt will also be made to provide aggregate data for those visits in New York City which are to free-standing clinics of various sorts. The AMA data base is adequate for sampling physicians providing care in these settings. The issue of visits to non-MD providers in OPDs, emergency rooms, and free-standing clinics, which is not addressed by AMA data, will be carefully considered using the AHA sample. There are two major products from this project: 1) A comprehensive description of hospital-based ambulatory visits in a major metropolitan area compared with visits to private practice. 2) An evaluation of sampling techniques which could be used nationwide and which could accurately reflect the distribution of non-private ambulatory visits. The major policy relevance of this proposal concerns the great disparities in reimbursement between private and clinic care, the major differences in populations served by the two types of settings, and possible considerable differences in resource consumption and type of care rendered.